Kutuk Zeynep Bilge, Gurgan Sevil, Hickel Reinhard, Ilie Nicoleta
Department of Restorative Dentistry, Hacettepe University, School of Dentistry, Sihhiye, Ankara, Turkey.
Department of Restorative Dentistry, Dental School of the Ludwig-Maximilians-University, Munich, Germany.
Am J Dent. 2017 Feb;30(1):9-15.
To investigate in vitro the effect of extremely high irradiance light-emitting diode (LED) light curing units (LCU) with different exposure distances and curing modes on the micromechanical properties of a nano hybrid resin based composite.
72 resin based composite (RBC) (Kalore) specimens with 2 mm thickness were cured using two high irradiance LED LCUs (Bluephase 20i and FlashMax P3) at 0 and 7 mm exposure distances. The curing conditions were:a) Bluephase 20i - 10 seconds - High power; b) Bluephase 20i - 15 seconds - High power; c) Bluephase 20i - 5 seconds - Turbo; d) Bluephase 20i - 15 seconds - Soft start; e) FlashMax P3 - 4 mm tip cover - 3 seconds; f) FlashMax P3 - without tip cover - 3 seconds. The incident and transmitted irradiance and radiant exposure were evaluated in real time during curing, with a radiometer (MARC Resin Calibrator). The micromechanical properties (Vickers hardness, HV and indentation modulus, E) were measured with an automatic universal hardness indenter after storing specimens for 24 hours in distilled water. Data were analyzed with one- and two-way ANOVA tests followed by Tukey test and partial eta-square statistics (α= 0.05).
For both LCUs, incident irradiance decreased progressively with increased exposure distance, reaching at 7 mm exposure distance less than 50% of the value measured when the LCU was applied directly on specimen's surface. In descending order of strength of their effects, the parameters incident irradiance (HV; η P2 =0.828, E; 0.693), LCU (HV, 0.257, E, 0.043) and exposure distance (HV, 0.031, E, 0.028) were significant factors affecting HV and E (P < 0.05). The localized radiant exposure (the incident and transmitted) as well as the position of HV and E measurements (top-bottom of the specimen) were additional factors affecting significantly only HV (P < 0.05), but not E (P > 0.05).
Extremely high irradiances were less efficient in adequate curing of the analyzed nano hybrid composite. Using a protection tip, as clinically indicated, reduces the irradiance of FlashMax P3 from 7,681.7 (160.53) mW/cm2; to 3052.5 (71.61) mW/cm2;.
在体外研究不同照射距离和固化模式的极高辐照度发光二极管（LED）光固化机（LCU）对纳米混合树脂基复合材料微观力学性能的影响。
使用两台高辐照度LED LCU（Bluephase 20i和FlashMax P3）在0和7mm照射距离下固化72个厚度为2mm的树脂基复合材料（RBC）（Kalore）试样。固化条件为：a）Bluephase 20i - 10秒 - 高功率；b）Bluephase 20i - 15秒 - 高功率；c）Bluephase 20i - 5秒 - 涡轮模式；d）Bluephase 20i - 15秒 - 软启动；e）FlashMax P3 - 4mm尖端罩 - 3秒；f）FlashMax P3 - 无尖端罩 - 3秒。在固化过程中使用辐射计（MARC树脂校准仪）实时评估入射和透射辐照度以及辐射暴露量。将试样在蒸馏水中储存24小时后，使用自动万能硬度压头测量微观力学性能（维氏硬度，HV和压痕模量，E）。数据采用单因素和双因素方差分析，随后进行Tukey检验和偏η²统计（α = 0.05）。
对于两台LCU，入射辐照度均随照射距离增加而逐渐降低，在7mm照射距离时降至低于将LCU直接应用于试样表面时测量值的50％。按其影响强度降序排列，参数入射辐照度（HV；η²P2 = 0.828，E；0.693）、LCU（HV，0.257，E，0.043）和照射距离（HV，0.031，E，0.028）是影响HV和E的显著因素（P < 0.05）。局部辐射暴露（入射和透射）以及HV和E测量位置（试样的顶部 - 底部）是仅显著影响HV（P < 0.05）而不影响E（P > 0.05）的其他因素。
极高辐照度在充分固化所分析的纳米混合复合材料方面效率较低。如临床所示，使用保护尖端可将FlashMax P3的辐照度从7,681.7（160.53）mW/cm²降低至3052.5（71.61）mW/cm²。
